Identifying mark



- 11 23, 1940. w. F. GREENWALD 2,198,162

IDENTIFYING MARK Filed March 15, 1959 DISAPPEARS 1N TEN MINUTES USE OFTHE BULB AND IS THE INVENTOR Patented Apr. 723, 1940 UNETED STATESPATENT OFFICE to General Electric Company,

Schenectady,

N. Y., a corporation of New York Application vMarch 15, 1939, Serial No.261,924

1 Claim.

This invention relates to identifying marks or labels, particularlythose applied to devices which becomeheated when subjected to normaluse. Various applications of the invention include the identification ofelectric lamp bulbs, radio tubes,

electric heating appliances, and the like.

Electric lamp bulbs and radio tubes usually have the manufacturerstrademark etched upon the glass or stamped on the base. Electric heatingappliances are ordinarily identified by attached tags, or labels ofvarious kinds. None of these afi'ord any assurance to the purchaser thatthe device is actually new, since the dealer may and often does selldevices which have been reconditioned or used and returned to stockwithout informing the purchaser of the facts. Purchasers often lose asubstantial part of the expected life of the product and pay more forthe product than it is actually worth. so It is the object of thepresent invention to provide a mark or label forvdevices which will beobliterated or will change color after the mark has been subjected tothe normal operating temperature thereof for a relatively brief period,25 thus affording a warning to the purchaser if the device has beenused, and assurance that it is new if the mark or label is in itsoriginal condition.

Other objects and advantages of the invention 30 will be understood byreference to the following specification and accompanying drawing, in

which:

Fig. 1 is a view in elevation of an electric light bulb embodying theinvention; 35 Fig. 2 is an end view of the bulb; and

Fig. 3 is a perspective view of an electric iron' illustrating theapplication of the invention.

The drawing is merely illustrative, it being evident that the inventionmay be applied in a 40 variety of different ways to different devices.Hence in describing particular applications of the invention, it is notmy intention to limit the generality of its use.

In utilizing the' invention, the mark or label 45 will usually consistof or include a trademark or similar identifying mark of themanufacturer. It may, however, consist merely of any mark, symbol orlegend. It may be applied to any part of the device where it will besubjected to the 50 normal temperature of the device in use.

Since electrical devices are often tested briefly before delivery to thecustomer, the mark should not be obliterated or changed in appearance bymomentary heating. The substance or com- 55 pound employed isconsequently such that a controllable time interval is required toeffect the change in appearance. The mark in the form of a suitablemedium is applied to any convenient surface where it will be subjectedto the normal operating temperatureof the device, by print- 5 ing,stamping, painting, decalcomania or otherwise.

Various materials are available for use in such media. These materialsinclude compounds, dyes or pigments which volatilize or lose or change19 their color on the application of heat, compounds, dyes or pigmentswith oxidizing agents which oxidize and destroy or change the color ofthe pigment when heat is applied, and various other compounds ormixtures which are similarly al:'- fected, such as those havingingredients which react upon the application of heat.

To illustrate the invention, reference is made to the drawing showing anelectric lamp bulb 5 having a mark 6 printed or otherwise dis- 20 posedon the glass. The ink used may be of such a nature that when thefilament I is lighted the heat generated will cause the mark to fade orto change color, for example, from red to black, after a brief interval.Hence the purchaser is advised that the bulb is new if the mark is inits original condition, or that it has been used if the mark isobliterated or changed in color.

Similarly, the mark 8 may be applied to the wall of an electricallyheated appliance, such as an electric iron 9. As soon as the device isused for any substantial period, the mark may disappear or change color,thereby indicating that the device is not new. Anyof the commonelectrically heated appliances may be so markedto ensure that the devicesold is actually new and unused.

The invention has a further advantage in that,

' if a trademark is used, the attention of the purchaser is directed tothe trademark which 0 identifies the manufacturer. The purchaser will bewarned to look for the mark to determine whether or not the device isnew. At the same time, he will be assured that he is getting a devicefrom the particular source which he prefers. Passing off of inferiormerchandise is thus avoided It is unnecessary to attempt to describe allsuitable media for the application of the mark. since there are numerousmaterials which alone or in combination will serve the purpose. Thefollowing examples will serve to illustrate various inks which may beused. Other inks, paints and decalcomania media of similar and differentParts Potassium chlorate -52 Potassium dichromate 3-4 Sulphur 5 Ferricoxide 10 Zinc oxide 7 Glue 10-15 3. An example of a change in colorwithout oxidation is:

Parts Antimony pentasulphide (golden antimony sulphide) 5 Ammoniumbisulphate 5 Enough alcoholic solution of shellac to make a binder. Onheating, this changes from orange to black. In the case of anincandescent bulb the mark would have to disappear, as it woulddisfigure the appearance of the bulb. With a radio tube,

however, that is not important, as the tube is enclosed in the radioset. The manufacturer would want his name to stay on the tube even afterthe tube has been in use, so that the purchaser could readily see it onrenewing tubes. Therefore on radio tubes a change in color would bepreferable.

The advantages of the invention in preventing substitution and the saleof used products as new are self-evident. The purchasing public with theminimum of efiort can readily detect attempts to dispose of inferiorproducts and ensure itself of full value for the money paid.

Various changes in the form, arrangement and mode of application of theinvention may be made without. departing from the invention orsacrificing the advantages thereof.

I claim:

An article of manufacture adapted to become heated in normal use havingan identifying mark comprising a medium applied to the surface of thearticle, which medium will withstand, without modification, heating atthe normal operating temperature of the article for a period long enoughto permit testing of the article, but will disappear upon heating for apredetermined period longer than that necessary for testing of thearticle.

WILLARD F. GREEN-WALD.

